Support arm



FIG. 1 is a front perspective view of a support arm showing the new design;

FIG. 2 is a rear perspective view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a rear view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a right side view thereof;

FIG. 7 is a top view thereof;

FIG. 8 is a bottom view thereof; and,

FIG. 9 is a front perspective view of the support arm in an environement.

Features illustrated in broken or dashed lines form no part of the claimed design. 

CLAIM The ornamental design for a support arm, as shown and described. 